Apparatus for manufacturing bead inductor

ABSTRACT

A method of producing a bead inductor includes the steps of forming an outer portion outside of a conductor coil, and forming a molded body with the conductor coil embedded therein. The outer portion is formed outside of the conductor coil by disposing the conductor coil in a cavity defined by first and second mold portions, with first and second gates formed in the first mold portion, inserting first and second spacer pin portions, which define a spacer pin which passes through the conductor coil and extends to and closes the second gate, and supplying material containing magnetic powder into the mold cavity from the first gate. The molded body is formed by closing the first gate after the formation of the outer portion, and supplying from the second gate material containing magnetic powder into a space formed by removing the spacer pin portions.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method of producing a beadinductor and an apparatus for producing a molded body to be included ina bead inductor.

[0003] 2. Description of the Related Art

[0004] Bead inductors are used as anti-noise or noise eliminationcomponents, particularly in microprocessors or other similar devices, inwhich a large amount of current needs is supplied and transmitted. Abead inductor consisting of a conductor coil embedded in rubber or resinmaterial containing magnetic powder (such as ferrite powder) is known.In general, in forming this type of bead inductor, a conductor coil isembedded in resin or rubber material via injection molding or the like,whereby a molded body is formed. Then, both ends of the molded body arecut to expose both ends of the coil embedded in the resin or the rubbermaterial. Thereafter, metallic caps which define external terminalelectrodes, are mounted on the exposed coil ends, for example, by usingan electrically conductive, resinous paste or via spot welding.

[0005]FIGS. 6 and 7 are sectional views illustrating a method ofproducing a molded body used to form a bead inductor via injectionmolding. It is noted that the subject matter shown in FIGS. 6 and 7 andthe description thereof contained herein has not yet been published.

[0006] Referring to FIG. 6, an injection mold, used to form a moldedbody to be included in a bead inductor, includes an upper mold portion 1and a lower mold portion 2. A cavity 3 in which resin is molded isformed in the upper mold portion 1. A space 3 a provided to form aprojecting portion on the molded body is formed above the cavity 3. Atthe lower mold portion 2, a spacer pin 4 is arranged to be locatedwithin the cavity 3 when the lower mold portion 2 and the upper moldportion 1 are fitted together. A gate 1 a used to supply molten resininto the cavity 3 is formed in the upper mold portion 1.

[0007] When a molded body used for forming a bead inductor is producedusing the mold of FIG. 6, a conductor coil, which is formed by windinginto a spiral or other shaped configuration, a metallic wire, such as acopper wire, coated with an insulating material, such as polyesterresin, is inserted onto the spacer pin 4. Then, molten resin containingmagnetic powder, such as ferrite powder, is injected into the cavity 3from the gate 1 a, causing an outer portion to be formed outside of theconductor coil inserted onto the spacer pin 4.

[0008]FIG. 7 is a sectional view showing a state in which the outerportion is formed outside of a conductor coil 5 using theabove-described method. As shown in FIG. 7, the conductor coil 5 isembedded in the molded body 6, and the spacer pin 4 is located inside ofthe conductor coil 5. This spacer pin 4 is pulled out of the molded body6 in order to allow formation of an inner portion located inside of theconductor coil 5.

[0009]FIGS. 8A, 8B, and 8C are sectional views illustrating the stepscarried out to form an inner portion inside of the conductor coil 5 viamolding. FIG. 8A illustrates the molded body 6, with the upper moldportion 1 and the lower mold portion 2 being separated from each otheras a result of moving the upper mold portion 1 upward from its positionshown in FIG. 7. The spacer pin 4 is disposed in the molded body 6, andis mounted on the lower mold portion 2. The molded body 6 has aprotruding portion 6 a at the top portion thereof. The protrudingportion 6 a is removed by cutting or a similar process, thereby,allowing the spacer pin 4 in the molded body 6 to be pulled upward andremoved therefrom.

[0010]FIG. 8B illustrates a state after removal of the spacer pin 4 bythe above-described method. A space 6 b is formed in the molded body 6as a result of the removal of the spacer pin 4. With the space 6 b beingformed in the molded body 6, the upper mold portion 1 is fitted onto thelower mold portion 2 again, as shown in FIGS. 6 and 7. From the gate 1a, molten resin is supplied into the mold so as to flow into the space 6b, causing an inner portion to be formed inside of the conductor coil 5.

[0011]FIG. 8C is a sectional view illustrating a state after formationof an inner portion inside of the conductor coil 5 via molding. Aprotruding portion 6 c corresponding to a configuration of the space 3 aof FIG. 6 is formed at the top portion of the molded body 6, while aprotruding portion 6 d is formed at the bottom portion of the moldedbody 6 so as to be disposed in the space in the lower mold portion 2where the spacer pin 4 was inserted.

[0012]FIG. 9 is a sectional view of the molded body 6 formed by theabove-described molding method. The conductor coil 5 is embedded in themolded body 6. The protruding portion 6 c is formed at the top portionof the molded body 6, while the protruding portion 6 d is formed at thebottom portion of the molded body 6. By cutting the molded body 6,using, for example, a dicing saw, along cutting lines A-A and B-B, theends of the conductor coil 5 in the molded body 6 are exposed. Metalliccaps are electrically connected and mounted to the exposed ends of theconductor coil 5, for example, by using electrically conductive resinouspaste or via spot welding.

[0013]FIGS. 10 and 11 are a side view and a plan view illustrating abead inductor having metallic caps mounted thereon. One end sa of theconductor coil 5 is electrically connected to a metallic cap 7, whilethe other end 5 b of the conductor coil 5 is electrically connected to ametallic cap 8. The metallic caps 7 and 8 are used as external terminalelectrodes.

[0014] In the above-described bead inductor and method of formingthereof, the spacer pin is removed after formation of the outer portionlocated outside of the conductor coil via molding. To remove the spacerpin, it is necessary to open the mold and to cut the protruding portionat the top portion of the molded body. This makes it difficult toautomate and simplify the injection molding cycle. Therefore, when theconventional bead inductor production method is used, molded bodiescannot be formed with high productivity.

SUMMARY OF THE INVENTION

[0015] To overcome the problems described above, preferred embodimentsof the present invention provide a method of manufacturing a beadinductor and a bead inductor molded body producing apparatus, whichachieve improved and highly efficient production of bead inductor moldedbodies having a conductor coil embedded therein.

[0016] According to a first aspect of preferred embodiments of thepresent invention, there is provided a method of producing a beadinductor, in which a molded body having a hollow core conductor coilembedded in rubber or resin material containing magnetic powder isformed, and in which both ends of the conductor coil in the molded bodyare exposed to electrically connect external terminal electrodes to bothof the exposed ends of the conductor coil, the method including thesteps of forming an outer portion outside of the conductor coil viamolding, by disposing the conductor coil in a cavity of a mold having afirst gate and a second gate formed therein, disposing a spacer pinwhich passes through the core of the conductor coil and extends up tothe second gate to close the second gate, and supplying the rubber orthe resin material containing magnetic powder into the mold cavity fromthe first gate and forming the molded body with the conductor coilembedded therein, by, after the formation of the outer portion outsideof the conductor coil, closing the first gate, pulling the spacer pinout of the mold cavity, and supplying from the second gate the rubber orthe resin material containing magnetic powder into a space formed as aresult of the removal of the spacer pin so as to extend through the coreof the conductor coil, in order to form an inner portion inside of theconductor coil.

[0017] In such a case, after the formation of the outer portion outsideof the conductor coil, the spacer pin is pulled out. When the outerportion is formed outside of the conductor coil via molding, the spacerpin is disposed so as to pass through the core of the conductor coil andto extend up to the second gate to close the second gate. When thespacer pin is pulled out, a space which extends through the core of theconductor coil from the second gate is formed. From the second gate,resin or rubber material is supplied into the space located inside ofthe conductor coil. In the first aspect, the outer portion does not haveto be removed after the formation of the outer portion outside of theconductor coil, so that the next step of forming an inner portion insideof the conductor coil can be carried out with the outer portion beingdisposed in the mold cavity.

[0018] The mold may have an accommodating hole for accommodating thespacer pin therein. When the outer portion is formed outside of theconductor coil via molding, a portion of the spacer pin may be pushedout of the accommodating hole and pushed into the mold cavity. On theother hand, when the inner portion is formed inside of the conductorcoil via molding, the spacer pin may be pulled out so that a portion ofthe spacer pin is accommodated in the accommodating hole.

[0019] In such a case, since an accommodating hole may be formed in themold to allow insertion and removal of the spacer pin into and out ofthe cavity, it possible to provide a an excellent and greatly improvedproduction method which allows automation and simplification of themolding process.

[0020] The mold may include an upper mold portion and a lower moldportion.

[0021] In such a case, since the mold may include an upper mold portionand a lower mold portion, it possible to stably and easily insert theconductor coil into the mold.

[0022] When the mold includes an upper mold portion and a lower moldportion, the spacer pin may be divided into a first spacer pin portionand a second spacer pin portion, the first spacer pin portion having ashape which fits into the accommodating hole formed in the lower moldportion, and the second spacer pin portion having a shape which fitsinto the second gate formed in the upper mold portion. In forming theouter portion outside of the conductor coil via molding, a portion ofthe first spacer pin portion and a portion of the second spacer pinportion of the spacer pin may be pushed into the mold cavity from theaccommodating hole and from the second gate, respectively, in order tobring the first spacer pin portion and the second spacer pin portioninto contact with each other, whereby the spacer pin is formed so as topass through the mold cavity. On the other hand, in forming the innerportion inside of the conductor coil via molding, the first spacer pinportion may be pulled out so that a portion thereof is accommodated inthe accommodating hole formed in the lower mold portion, and the secondspacer pin portion may be pulled out and removed out of the mold fromthe second gate.

[0023] In such a case, the spacer pin may be divided into a first spacerpin portion and a second spacer pin portion and formed so as to passthrough the mold cavity. In forming the outer portion outside of theconductor coil via molding, a spacer pin may be formed by pushing aportion of the first spacer pin portion and a portion of the secondspacer pin portion into the mold cavity and causing the first and secondspacer pin portions to contact each other. Thus, compared to the casewhere one spacer pin is pushed into the mold cavity from the lower moldportion so that the spacer pin passes through the mold cavity and isinserted into the second gate formed in the upper mold portion to closeit, the upper mold portion and the lower mold portion can be easilydesigned so that they are, for example, positioned precisely withrespect to each other.

[0024] When the spacer pin is divided into a first spacer pin portionand a second spacer pin portion and formed so as to pass through themold cavity, the first gate may be formed in the upper mold portion.

[0025] In such a case, since the first gate may be formed in the uppermold portion, it is much easier to design, for example, a moldingmachine or a mold.

[0026] In the case where the spacer pin is divided into a first spacerpin portion and a second spacer pin portion and formed so as to passthrough the mold cavity, or in the case where the first gate is formedin the upper mold portion, when the conductor coil is disposed in themold cavity, a portion of the first spacer pin portion may be pushed outof the accommodating hole, and the core of the conductor coil may bemounted onto the first spacer pin portion in order to position theconductor coil in the cavity.

[0027] In such a case, since the conductor coil may be positioned byinserting the core of the conductor coil onto the first spacer pinportion, it is much easier to design a molding machine.

[0028] In forming the inner portion inside of the conductor coil viamolding, the first gate may be closed by inserting a closing pin intothe first gate.

[0029] In such a case, since the first gate may be closed by inserting aclosing pin into the first gate, the structure of, for example, amolding machine or a mold is greatly simplified.

[0030] When the first gate is closed by inserting a closing pin, afterthe formation of the inner portion inside of the conductor coil viamolding, the molded body may be ejected from the mold by pushing aportion of the closing pin out of the first gate and inserting theportion of the closing pin into the mold cavity.

[0031] In such a case, since the molded body may be ejected from themold via the closing pin used to close the first gate, the structure of,for example, a molding machine or a mold can be greatly simplified, andthe molded body can be automatically ejected after molding.

[0032] In the case where the first gate is closed by inserting a closingpin into it or in the case where the molded body is ejected from themold by using the closing pin used to close the first gate, during theformation of the inner portion inside of the conductor coil via molding,the second spacer pin portion which is removed out of the mold may beused as the closing pin for insertion into the first gate.

[0033] In such a case, since the second spacer pin portion may be usedas the closing pin, the structure of, for example, a molding machine ora mold can be greatly simplified.

[0034] A molding cycle including the steps of inserting the conductorcoil into the mold cavity, forming the outer portion outside of theconductor coil via molding, forming the inner portion inside of theconductor coil via molding, and ejecting the molded body from the moldmay be repeated by automatic control.

[0035] In such a case, since the molding process carried out to form abead inductor molded body may be automated, it is possible to increaseoperation efficiency of a molding machine, and to mass-produce moldedbodies economically.

[0036] According to another aspect of preferred embodiments of thepresent invention, there is provided an apparatus for producing a moldedbody to be included in a bead inductor, in which the molded body isformed in a mold cavity via injection molding when producing the beadinductor by electrically connecting external terminal electrodes to bothends of a hollow core conductor coil disposed in the molded body formedby embedding the hollow core conductor coil in rubber or resin materialcontaining magnetic powder, the apparatus including an upper moldportion having a first gate and a second gate arranged to allow rubberor the resin material containing magnetic powder to be supplied into themold cavity, a lower mold portion which is fitted to the upper moldportion to define the mold cavity, the lower mold portion having anaccommodating hole in a portion thereof located at a position incorrespondence with a substantially center portion of the mold cavity, afirst spacer pin portion arranged to be movably disposed in theaccommodating hole in the lower mold portion, a second spacer pinportion arranged to be movably disposed in the second gate in the uppermold portion, and a closing pin arranged to be movably disposed in thefirst gate in the upper mold portion, wherein after insertion of thecore of the conductor coil onto the first spacer pin portion, a portionof which first spacer pin portion is upwardly pushed out of theaccommodating hole formed in the lower mold portion, the upper moldportion and the lower mold portion are fitted together to define thecavity used for the injection molding, the second spacer pin portion ispushed downward so that a portion thereof is pushed out of the secondgate in the upper mold portion in order to bring the second spacer pinportion into contact with the first spacer pin portion, whereby a spacerpin which passes through the cavity is formed. In this state, the rubberor the resin material containing magnetic powder is supplied into thecavity from the first gate to form an outer portion outside of theconductor coil the molding. After the molding, the first spacer pinportion is pulled out so that a portion thereof is accommodated in theaccommodating hole formed in the lower mold portion, and the secondspacer pin portion is pulled out and removed out of the mold from thesecond gate. A closing pin is inserted into the first gate to close thefirst gate. From the second gate, the rubber or the resin materialcontaining magnetic powder is supplied into a space formed inside of theconductor coil, by pulling out the first spacer pin portion and thesecond spacer pin portion, whereby the molded body having the conductorcoil embedded therein is formed.

[0037] In such a case, after the formation of the outer portion outsideof the conductor coil via molding, an inner portion can be formed insideof the conductor coil, without taking out the outer portion from themold. This makes it possible to produce molded bodies efficiently andeasily.

[0038] In the above-described device, the closing pin may be used as thesecond spacer pin portion.

[0039] In such a case, the structure of, for example, an injection moldor a mold can be greatly simplified. This makes it possible to automatethe molding process and to reduce molding costs.

[0040] When the apparatus according to preferred embodiments of thepresent invention is used or when the closing pin is used as the secondspacer pin portion, after the formation of the molded body with theconductor coil embedded therein, the upper mold portion and the lowermold portion which have been fitted together may be separated from eachother, and the closing pin may be moved downward to push out and ejectthe molded body from the cavity.

[0041] In such a case, since the molded body may be pushed out of andejected from the cavity by moving the closing pin downward, the moldedbody can be easily taken out, and the molding process can be automated.

[0042] For the purpose of illustrating the invention, there is shown inthe drawings several forms which are presently preferred, it beingunderstood, however, that the invention is not limited to the precisearrangements and instrumentalities shown.

BRIEF DESCRIPTION OF THE DRAWINGS

[0043]FIG. 1 is a sectional view illustrating a method of producing amolded body to be included in a bead inductor, according to a preferredembodiment of the present invention.

[0044]FIG. 2 is a sectional view illustrating a method of producing amolded body to be included in a bead inductor, according to a preferredembodiment of the present invention.

[0045]FIG. 3 is a sectional view illustrating a method of producing amolded body to be included in a bead inductor, according to a preferredembodiment of the present invention.

[0046]FIG. 4 is a sectional view illustrating a method of producing amolded body to be included in a bead inductor, according to a preferredembodiment of the present invention.

[0047]FIG. 5 is a sectional view illustrating a method of producing amolded body to be included in a bead inductor, according to a preferredembodiment of the present invention.

[0048]FIG. 6 is a sectional view illustrating a related process ofproducing a molded body to be included in a bead inductor.

[0049]FIG. 7 is a sectional view illustrating the related process ofproducing a molded body to be included in a bead inductor.

[0050]FIGS. 8A, 8B, and 8C are sectional views illustrating the relatedprocess of producing a molded body to be included in a bead inductor.

[0051]FIG. 9 is a sectional view of a molded body produced by therelated production method.

[0052]FIG. 10 is a side view of a bead inductor.

[0053]FIG. 11 is a plan view of the bead inductor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0054]FIG. 1 is a sectional view of a mold of an apparatus for producinga molded body to be included in a bead inductor, according to apreferred embodiment of the present invention. This mold is used to forma molded body via injection molding. The mold preferably includes anupper mold portion 11 and a lower mold portion 12. As shown in FIG. 1,when the upper mold portion 11 and the lower mold portion 12 are fittedtogether, a cavity 13 is formed. A molded body will be formed in thecavity 13 as described below.

[0055] A first gate 14 and a second gate 15 are provided at the uppermold portion 11. The first gate 14 and the second gate 15 are arrangedto allow rubber or molten resin containing magnetic powder to flow intothe cavity 13. An accommodating hole 16 is formed in a portion of thelower mold portion 12 located so as to correspond to a location of theapproximate center portion of the cavity 13. A first spacer pin portion18 is movably disposed in the accommodating hole 16. A second spacer pinportion 17 is movably disposed in the second gate 15 formed in the uppermold portion 11.

[0056] In the state shown in FIG. 1, the first spacer pin portion 18 andthe second spacer pin portion 17 are both pushed into the cavity 13 sothat an end portion 18 a of the first spacer pin portion 18 and an endportion 17 a of the second spacer pin portion 17 contact each other. Aclosing pin (described later) can be movably disposed in the first gate14. In the state shown in FIG. 1, the closing pin is disposed outsidethe mold.

[0057] A conductor coil 10 is inserted onto the first spacer pin portion18. The coil 10 is preferably formed as an hollow core conductor coilby, for example, winding in a spiral or other configuration, a metallicwire (such as a copper wire) coated with an insulating material (such aspolyester resin).

[0058] A description will now be given of the steps carried out to forma bead inductor molded body using the injection mold of FIG. 1, inaccordance with preferred embodiments of the present invention.

[0059] As shown in FIG. 2, when the conductor coil 10 is being placed inthe mold, the mold is in an open state, with the upper mold portion 11being located separate from and above the lower mold portion 12, and thelower mold portion 12 being disposed below the upper mold portion 11.With the mold in the open state, a portion of the first spacer pinportion 18 is pushed upward from the through hole 16 in the lower moldportion 12. The conductor coil 10 is disposed in the mold by insertingthe hollow core of the conductor coil 10 onto the first spacer pinportion 18, so that the conductor coil 10 is fitted onto the firstspacer pin portion 18. In other words, the conductor coil 10 ispositioned in the cavity 13 by inserting the conductor coil 10 onto thefirst spacer pin portion 18.

[0060] The first gate 14 formed in the upper mold portion 11 is in anopen state. The second spacer pin portion 17 is inserted into the secondgate 15 so that the end portion 17 a of the second spacer pin portion 17is pushed downward and protrudes from the second gate 15. With thesecond spacer pin portion 17 protruding from the second gate 15, theupper mold portion 11 is moved downward relative to the lower moldportion 12 in order to fit the upper and lower mold portions 11, 12together, as shown in FIG. 1. As shown in FIG. 1, the end portion 18 aof the first spacer pin portion 18 and the end portion 17 a of thesecond spacer pin portion 17 are brought into contact with each other inthe cavity 13, whereby a spacer pin which passes through the cavity 13in the vertical direction so as to pass through the hollow core of thecoil 10 is formed. It is to be noted that the second spacer pin portion17 does not necessarily have to be moved downward before fitting theupper mold portion 11 and the lower mold portion 12 together. The secondspacer pin 17 may be moved downward so that the end portion 17 a thereofcomes into contact with the end portion 18 a of the first spacer pinportion 18 after fitting the upper mold portion 11 and the lower moldportion 12 together.

[0061] In the state shown in FIG. 1, molten rubber or molten resincontaining magnetic powder is injected into the cavity 13 from the firstgate 14 to form an outer portion outside of the conductor coil 10 viamolding. Since the spacer pin defined by the first spacer pin portion 18and the second spacer pin portion 17 is disposed in the cavity 13, resinis molded in the area around the spacer pin.

[0062]FIG. 3 illustrates a state after formation of an outer portionoutside of the conductor coil 10 using the above-described moldingmethod. In the cavity 13, a molded body 20 is formed outside of theconductor coil 10. After the formation of the molded body 20, the firstspacer pin portion 18 is moved downward and pulled out of the moldedbody 20. The first spacer pin portion 18 is moved until its top end 18 ais level with the top surface of the lower mold portion 12. Then, thefirst spacer pin portion 18 is fixed at that location.

[0063] The second spacer pin portion 17 is moved upward and pulled outof the molded body 20. Then, the second spacer pin portion 17 is pulledup through the second gate 15 and removed out of the mold. Pulling thefirst spacer pin portion 18 and the second spacer pin portion 17 out ofthe molded body 20 causes a space 21 to be formed in the approximatecenter portion of the molded body 20. The space 21 is formed so as toextend through the core of the conductor coil 10 and so as to lead tothe second gate 15. A closing pin 19 is inserted into the first gate 14in order to close the first gate 14.

[0064]FIG. 4 illustrates the first gate 14 which has been closed as aresult of inserting the closing pin 19 into the first gate 14. When thefirst gate 14 is closed, the second gate 15 leads to the space 21 in theapproximate center portion of the molded body 20, and the space 21 leadsto a portion located inside of the conductor coil 10.

[0065] Similar to the formation of the molded body 20, molten rubber ormolten resin material is injected into the space 21 from the secondgate-15 so as to form in the space 21 an inner portion inside of theconductor coil 10.

[0066]FIG. 5 is a sectional view illustrating a state after formation ofan inner portion inside of the molded body 20, in the space 21, usingthe above-described method. As shown in FIG. 5, filling the space 21 inthe approximate center portion of the molded body 20 (shown in FIG. 4)results in the formation of a molded body 22 having the conductor coil10 embedded therein. In the molded body 22 shown in FIG. 5, the core ofthe conductor coil 10 is also filled with resin or rubber material,which is preferably molded.

[0067] After the formation of the molded body 22, the upper mold portion11 is moved upward relative to the lower mold portion 12 and separatedtherefrom, whereby the mold is opened, as shown in FIG. 5. Molded bodies22 having the conductor coil 10 embedded therein tend to remain fittedto the upper mold portion 11 in which cavity 13 is formed. In such acase, molded bodies 22 are ejected from the upper mold portion 11 bymoving the closing pin 19 in the first gate 14 downward and pushing outthe molded bodies 22.

[0068] As described above, a molded body 22 with a conductor coil 10embedded therein is produced. In the next molding cycle after theejection of the molded body 22 from the mold, the first spacer pinportion 18 is moved upward in order to set the mold in the state shownin FIG. 2. Then, the conductor coil 10 is inserted onto the first spacerpin portion 18 to form the next molded body.

[0069] Like the ends of the molded body of FIG. 9 produced by therelated method, both ends of the molded body 22 obtained by theabove-described method are cut with a dicing saw or similar device sothat the ends of the conductor coil are exposed. Like the exposed endsshown in FIGS. 10 and 11, the exposed ends of the conductor coil in thepreferred embodiments have external terminal electrodes, such asmetallic caps, mounted thereon so as to complete a bead inductor.

[0070] As can be understood from the foregoing description, according topreferred embodiments of the present invention, after formation of anouter portion outside of the conductor coil 10 via molding, an innerportion can be formed inside of the conductor coil 10 without taking themolded body 20 out of the mold. Therefore, molded bodies used to formbead inductors can be efficiently produced. Since manual operations donot have to be carried out during the molding process, the moldingprocess can be automatically controlled, making it possible to repeat byautomatic control the molding process cycle which includes placing theconductor coil into a mold, forming an outer portion outside of theconductor coil via molding, forming an inner portion inside of theconductor coil via molding, and ejecting the molded body. Therefore,molded bodies can be automatically produced, and operation efficiency ofthe injection mold can be greatly increased, allowing a large number ofmolded bodies to be produced with high efficiency.

[0071] Although in the above-described preferred embodiment, as shown inFIG. 3, the second spacer pin portion 17 is pulled out of the mold andthe first gate 14 is closed by inserting a closing pin 19 therein, thefirst gate 14 can be closed by inserting therein the second spacer pinportion 17 pulled out of the mold from the second gate 15. In otherwords, the second spacer pin portion 17, instead of the closing pin 19,can be used as closing pin.

[0072] According to one aspect of preferred embodiments of the presentinvention, there is provided a method of producing a bead inductor, inwhich after the formation of the outer portion outside of the conductorcoil, molded bodies with a conductor coil embedded therein can beproduced by forming an inner portion inside of the conductor coil,without taking out the outer portion from the mold. This makes itpossible to produce molded bodies used to form bead inductors veryefficiently and automatically.

[0073] An accommodating hole may be formed in the mold to allowinsertion and removal of the spacer pin into and from the cavity. Thismakes it possible to provide an improved production method which allowsautomation of the molding process.

[0074] The mold may include an upper mold portion and a lower moldportion. This makes it possible to stably dispose the conductor coil inthe mold.

[0075] When the mold includes an upper mold portion and a lower moldportion, the spacer pin may be divided into a first spacer pin portionand a second spacer pin portion and formed so as to pass through themold cavity. Here, the spacer pin is formed by bringing the first spacerpin portion and the second spacer pin portion into contact with eachother in the cavity, thereby making it easier to design the upper moldportion and the lower mold portion so that they are, for example,positioned precisely with respect to each other.

[0076] When the spacer pin is divided into a first spacer pin portionand a second spacer pin portion and formed so as to pass through themold cavity, the first gate may be formed in the upper mold portion.This makes it easier to design, for example, a molding machine or amold.

[0077] When the spacer pin is divided into a first spacer pin portionand a second spacer pin portion and formed so as to pass through themold cavity, or when the first gate and the second gate are formed inthe upper mold portion, the conductor coil may be positioned byinserting the core of the conductor coil onto the first spacer pinportion. This makes it easier to design a molding machine.

[0078] The first gate may be closed by inserting a closing pin into it.This simplifies the structure of, for example, a molding machine or amold.

[0079] When the first gate is closed by inserting a closing pin into it,the molded body may be ejected from the mold by using the closing pinused to close the first gate. This simplifies the structure of, forexample, a molding machine or a mold, and allows the molded body to beejected automatically after molding.

[0080] When the first gate is closed by inserting a closing pin into itor when the molded body is ejected from the mold via the closing pinused to close the first gate, the second spacer pin portion may be usedas the closing pin. This simplifies the structure of, for example, amolding machine or a mold.

[0081] A molding process including the steps of inserting the conductorcoil into the mold cavity, forming the outer portion outside of theconductor coil via molding, forming the inner portion inside of theconductor coil via molding, and ejecting the molded body from the moldcan be repeated by automatic control. This makes it possible to automatethe molding process carried out to form a bead inductor molded body,making it possible to increase operation efficiency of the moldingmachine, and to mass-produce molded bodies economically.

[0082] According to another aspect of preferred embodiments of thepresent invention, there is provided an apparatus for producing a moldedbody to be included in a bead inductor, in which after the formation ofthe outer portion outside of the conductor coil via molding, an innerportion can be formed inside of the conductor coil, without taking outthe outer portion from the mold. This makes it possible to producemolded bodies efficiently.

[0083] In the aforementioned device, the closing pin may be used as thesecond spacer pin portion. Therefore, the structure of, for example, aninjection mold or a mold can be simplified. This makes it possible toautomate the molding process and to greatly reduce molding costs.

[0084] When the apparatus according to preferred embodiments of thepresent invention is used or when the closing pin is used as the secondspacer pin portion, the molded body may be pushed out of and ejectedfrom the cavity by moving the closing pin downward. This allows themolded body to be easily and automatically ejected.

[0085] While preferred embodiments of the invention have been disclosed,various modes of carrying out the principles disclosed herein arecontemplated as being within the scope of the following claims.Therefore, it is understood that the scope of the invention is not to belimited except as otherwise set forth in the claims.

What is claimed is:
 1. A method of producing a bead inductor including amolded body having a hollow core conductor coil embedded in rubber orresin material containing magnetic powder, and in which both ends of theconductor coil in the molded body are exposed to electrically connectexternal terminal electrodes to both of the exposed ends of theconductor coil, the method comprising the steps of: forming an outerportion outside of the conductor coil via molding by disposing theconductor coil in a cavity of a mold having a first gate and a secondgate, disposing a spacer pin which passes through the core of theconductor coil and extends up to the second gate to close the secondgate, and supplying the resin or the rubber material into the moldcavity from the first gate; and forming the molded body with theconductor coil embedded therein, by, after the formation of the outerportion outside of the conductor coil, closing the first gate, removingthe spacer pin from the mold cavity, and supplying from the second gatethe resin or the rubber material into a space formed as a result of theremoval of the spacer pin so as to extend through the core of theconductor coil, in order to form an inner portion inside of theconductor coil.
 2. A method of producing a bead inductor according toclaim 1, wherein the mold has an accommodating hole for accommodatingthe spacer pin therein, and wherein when the outer portion is formedoutside of the conductor coil via molding, the spacer pin is pushed outof the accommodating hole and pushed into the mold cavity, whereas whenthe inner portion is formed inside of the conductor coil via molding,the spacer pin is pulled out so that the spacer pin is accommodated inthe accommodating hole.
 3. A method of producing a bead inductoraccording to claim 1, wherein the mold includes an upper mold portionand a lower mold portion.
 4. A method of producing a bead inductoraccording to claim 3, wherein the spacer pin is divided into a firstspacer pin portion and a second spacer pin portion, the first spacer pinportion having a shape which fits into the accommodating hole, and thesecond spacer pin portion having a shape which fits into the secondgate; wherein in forming the outer portion outside of the conductor coilvia molding, a portion of the first spacer pin portion and a portion ofthe second spacer pin portion of the spacer pin are pushed into the moldcavity from the accommodating hole and from the second gate,respectively, in order to bring the first spacer pin portion and thesecond spacer pin portion into contact with each other, whereby thespacer pin is formed so as to pass through the mold cavity; and whereinin forming the inner portion inside of the conductor coil via molding,the first spacer pin portion is pulled out so that the first spacer pinportion is accommodated in the accommodating hole formed, and the secondspacer pin portion is pulled out and removed out of the mold from thesecond gate.
 5. A method of producing a bead inductor according to claim4, wherein the first gate is formed in the upper mold portion.
 6. Amethod of producing a bead inductor according to claim 4, wherein whenthe conductor coil is disposed in the mold cavity, the first spacer pinportion is pushed out of the accommodating hole, and the core of theconductor coil is inserted onto the first spacer pin portion in order toposition the conductor coil in the cavity.
 7. A method of producing abead inductor according to claim 1, wherein in forming the inner portioninside of the conductor coil by molding, the first gate is closed byinserting a closing pin into the first gate.
 8. A method of producing abead inductor according to claim 7, wherein after the formation of theinner portion inside of the conductor coil by molding, the molded bodyis ejected from the mold by pushing the closing pin out of the firstgate and inserting the closing pin into the mold cavity.
 9. A method ofproducing a bead inductor according to claim 7, wherein during theformation of the inner portion inside of the conductor coil via molding,the second spacer pin portion which is removed out of the mold is usedas the closing pin for insertion into the first gate.
 10. A method ofproducing a bead inductor according to claim 1, wherein a molding cycleincluding the steps of inserting the conductor coil into the moldcavity, forming the outer portion outside of the conductor coil viamolding, forming the inner portion inside of the conductor coil viamolding, and ejecting the molded body from the mold is repeated byautomatic control.
 11. An apparatus for producing a molded body to beincluded in a bead inductor, in which the molded body is formed in amold cavity via injection molding when producing the bead inductor byelectrically connecting external terminal electrodes to both ends of ahollow core conductor coil disposed in the molded body formed byembedding the hollow core conductor coil in rubber or resin materialcontaining magnetic powder, the apparatus comprising: an upper moldportion having a first gate and a second gate arranged to allow theresin or the rubber material to be supplied into the mold cavity; alower mold portion which is fitted to the upper mold portion to definethe mold cavity, the lower mold portion having an accommodating hole ina portion thereof located a position substantially corresponding to anapproximate center portion of the mold cavity; a first spacer pinportion movably disposed in the accommodating hole in the lower moldportion; a second spacer pin portion movably disposed in the second gatein the upper mold portion; and a closing pin movably disposed in thefirst gate in the upper mold portion.
 12. An apparatus according toclaim 11, wherein after the core of the conductor coil is inserted ontothe first spacer pin portion which is upwardly pushed out of theaccommodating hole formed in the lower mold portion, the upper moldportion and the lower mold portion are arranged to be fitted together todefine the cavity used for the injection molding.
 13. An apparatusaccording to claim 11, wherein the second spacer pin portion is arrangedto be pushed downward so that the second spacer pin portion is pushedout of the second gate in the upper mold portion in order to bring thesecond spacer pin portion into contact with the first spacer pin portionso as to define a spacer pin which passes through the cavity.
 14. Anapparatus according to claim 11, wherein the first gate is arranged suchthat the resin or the rubber material is supplied into the cavity fromthe first gate to define an outer portion outside of the conductor coilvia molding.
 15. An apparatus according to claim 14, wherein after themolding, the first spacer pin portion is pulled out so that the firstspacer pin portion is accommodated in the accommodating hole formed inthe lower mold portion, and the second spacer pin portion is pulled outand removed out of the mold from the second gate, the closing pin isinserted into the first gate to close the first gate, and from thesecond gate the resin or the rubber material is supplied into a spaceformed inside of the conductor coil, by pulling out the first spacer pinportion and the second spacer pin portion, whereby the molded body withthe conductor coil embedded therein is formed.
 16. An apparatusaccording to claim 11, wherein the closing pin is used as the secondspacer pin portion.
 17. An apparatus according to claim 11, whereinafter the formation of the molded body with the conductor coil embeddedtherein, the upper mold portion and the lower mold portion which havebeen fitted together are separated from each other, and the closing pinis moved downward to push out and eject the molded body from the cavity.